My 355 has developed some problems lately. At first I was thinking fuel starvation, but when I pulled the aircleaner off, the carb and inside of the aircleaner lid were really black with carbon. If I ease it up to speed, I can get it all the way up to 6 grand. If I just drop the hammer on it it will pull hard up to 2800, then fall flat on its face every time. Just going by how it feels it seems like fuel starvation, but with all the Carbon and the backfiring through the Carb, I am more inclined to think it is an ignition problem. My ignition is HEI, but I used the Pertronix "Flamethrower" kit that came with Cap, Coil, and a funky looking Module. I am thinking that the most likely problem would be that module, so what I am wondering is if I can put the Stock GM Module back in, but still use the Hot Pertronix Coil? Or will the Hot coil fry the Stock Module?
plug wires will act just like a bad carb somtimes, also i would check the advance weights in the distributor to make sure they're not sticking. you may need softer springs on your advance weights also. and check the vacume advance to make sure it's working properly. i had a pertronix ignitor conversion kit in a points distributor and it worked perfectly. it's in a buddys car now and runs great it's 6 or 7 years old and hasn't missed a beat. and check your distributor shaft for too much play i've seen them raise up far enough to knock the cap off the distributor.
I didn't think about the weights sticking, that may well be the problem. Plug wires are less than a year old. I ended up using the Medium set of springs that came with the Pertronix kit. It has been running for two years with no problems until the last couple of weeks. The vacuum advance doesn't work and never has. Only thing I can figure is the 292 cam. I don't have vacuum anywhere, even directly off the manifold. At least not enough to feel. I run it with the distributor advanced as far as I can go and still be able to start it. Even without the vacuum advance I never had any problems until lately. It always pulled hard up to 6500 with no noticable timing problems so I never worried about it.
Excellent tips on tuning mech and vac advance in HEI http://forums.performanceyears.com/6/ubb.x?a=tpc&s=7286011111&f=6406082911&m=7546072852
If you wind up at a dead end after checking out the ignition, you might look into the possibility of a flat cam, weak/broken valvespring, or leaking intake valve. I had a VERY similar problem once, turned out to be a flat cam. I know a flat cam on a chevy seems like a stretch, but.....
The plugs look good, I pulled them first. I don't think its got anything to do with the Valvetrain because it doesn't do it all the time. I can nail it and have it fall flat on its face one minute, then nail it again and it screams just like it used too. Started out doing it every once in a while, now it does it more often than not. I pulled the cap a while ago and while the weights had a little rust on them, they moved freely. The cap and rotor still look good. The wires are less than a year old and I didn't find any burns on them. I think its in the Pertronix stuff somewhere. I pulled all the connections loose to check them for corrosion, but they all look clean too. I drove it today for about 30 miles. Running down the highway at a steady speed, it will cut out every twenty or thirty seconds. Just long enough to feel it, then right back to normal. Sometimes when it gets under a load like climbing a hill, it would cut out until I let off the gas and let the rpm drop a little. Climb the next hill and it runs fine all the way to the top. It really feels like the fuel supply is stuttering at times, but I have checked the entire fuel system, even going as far as pulling the top off the Carb. It had a little water in the bowl and I thought that was the problem, but it wasn't.
The Jalopy Journal
